1. Field of the Invention
The present invention relates to a method for wiring connections in a liquid crystal display device and structure for wiring connections to be used therefor.
2. Description of the Prior Art
FIG. 1 is a partially enlarged plane view showing a wiring connection structure in which an electrode 5 formed on a film-like printed circuit substrate 4 as a tape carrier (Tape automated bonding; hereinafter merely called "TAB") and a flexible printed circuit substrate (hereinafter merely called "FPC") is connected to another electrode 3 formed at a substrate 2a at the side of a displaying cell 1 of a liquid crystal display device.
In FIG. 1, the electrode 3 on one substrate 2a which is formed as to be partially overhung from the displaying area A of the displaying cell 1 is for example a common electrode, and a segment electrode (not illustrated) is formed at another substrate 2b so arranged as to be confronted through a liquid crystal layer (not illustrated) to the substrate 2a. An anisotropic conductive film 6 is adhered to the intermediate position on the surface of the portion overhung from the displaying area A of the substrate 2a that it can be intercrossed with the electrode 3. The film-like printed circuit substrate 4 is laminated so as to secure the matching between the electrode 5 and the electrode 3 on the substrate 2a therefrom. Namely, the electrode at the side of the substrate 2a and the electrode 5 at the side of the film-like printed circuit substrate 4 are electrically connected by way of an anisotropic conductive film 6. This anisotropic conductive film 6 is a conductive film which permit conductivity only in the vertical direction in FIG. 1. Therefore, the adjacent electrodes 3 and 5 are never short-circuited through anisotropic conductive film 6.
In the wiring connection structure described above, if the film-like printed circuit substrate 4 is peeled off once from the substrate 2a at the side of the displaying cell 1 for correcting of a positional error or repair of the breaking of wire or leakage in the case that any positional error should occur between the electrode 3 of the substrate 2a at the side of the displaying cell 1 and the electrode 5 of the film-like printed circuit substrate 4, or in the case it is detected in the inspection process that the connected point is broken or the current leaks therethrough, the electrode 3 on the substrate 2a at the side of the displaying cell 1 is apt to be peeled off. Especially, as the electrode 3 is not directly formed on the substrate 2a but the electrode 3 is formed on an overcoated film comprising resin to shield the color filter in the case of a color liquid crystal display device, the electrode 3 is apt to be peeled off much more.
For this reason, even though the electrode 5 of the film-like printed circuit substrate 4 is connected onto the electrode 3 of the substrate 2a at the side of the displaying cell 1 again after correcting the positional error or repairing such a fault as breaking of wire, the reliability of the connected portion may be remarkably lowered. Conventionally, re-connection has not been carried out.
Actually however, in the case that substrates in which positional error or breaking of wire occurs in the connected portion thereof as in the conventional examples are disposed as defective substrate, the ratio of completeness of the products may be remarkably lowered, thereby causing the cost of production to be much increased.